The only one i bother to look at is the base. 2136 means your hotel spend (less taxes, fees, etc.) is $213.6. The elite is the multiplier. you are getting 50% more points on top. The extra is a black box. whatever promo, points instead of breakfast, etc. crap goes in there.

95%+ of my stays are billed in non $US so it is basically impossible to check as you can never be sure what currency conversion rate is being used. Back in the SPG days some hotels used some pretty outlandish conversion rates so I assume that is still occurring with Marriott but who knows.

For 2019, I have received both a birthday elite night credit, and a Visa $3k spend elite night credit (yay January birthday). I also already have several stays adding up to additional elite night credits. The problem I have, is they don't add up and my total is short. But it is impossible to tell which are missing and which are there. Very frustrated that they can't even get the elite night credit total added up correctly.

Maybe it's just not that important? As long as it's in the ballpark I expect, I simply don't worry about it.

This. Pre-Merger, in a decade of stays the only gross error I've ever had was when a stay in SEK got converted to points as if they were in USD (approx 7x) ... I just waited, and sure enough, the "extra" points were clawed back (as it should have been).

Pre-merger, once a stay credited- which sometimes if you had back-to-back reservations at the same property could take 10 days for the 2nd one to post- spot-checks showed they were correct enough- and I'd only had a missing stay maybe twice in a decade.

I urge anybody getting charged in non-USD currency to double check their base points for my five last stays charged in GBP I only got between 10% to 25% of the expected base points.
I also got 2K points for an award stay with zero charge to the room. 1K was welcome gift but the other 1K no idea what it was , stay was at Sheraton Stockholm charged in SEK.
Maybe I got points for the room rate MAR pays to the Hotel...who knows ...

You pay the hotel. The hotel pays its franchise or management fee to Marriott later.

The main transaction where Marriott pays the hotel is award nights, in which case you don't earn "base points".

Yes that is obvious ... what I meant is that some genius at MAR IT launched a version of production that translates award nights as a cash value depending on what MAR paid the Hotel ... in whatever case I got 1K points on an award stay (541 Base + 406 Elite + 1,000 Extra) that I shouldn't have been awarded.

I'm completely frustrated by the lack of transparency on how points are posted. SPG was far more detailed. How have legacy Marriott customers accepted this?

The unbelievable thing is their IT system is apparently 2 years old, so don't expect that it will be changing anytime soon. I remember someone on FT saying that it is "Cloud based" which is why it is so much better than what Starwood had. Yeah right.

OP, I keep a spreadsheet which I update every time I make a new reservation. I calculate the expected earnings from that stay, and then update it when it actually posts. It's the only way to make sure you aren't missing points if you have multiple stays that may take weeks to post.